1. Field of the Invention
The present invention relates to an apparatus and a method of data backup using a video tape recorder, and more particularly to an apparatus and a method of data backup using a video tape recorder in which a backup function for converting a digital data of a host computer into a video signal and recording/reading onto/from a video tape and a unique function of the video tape recorder are integrated.
2. Description of the Related Art
Recently, substantial changes have occurred in a memory device for storing personal computer (PC) data in accordance with a development in personal computer technology. floppy disks and hard disks are widely used memory devices in a PC. Generally, the hard disk has a storage capacity extremely larger than those of other memory device. However, the hard disk is easily damaged by an electrical or physical impact.
Generally, because a single PC uses a single hard disk, the data in the hard disk needs to be periodically stored into an auxiliary memory device in order to protect the data stored in the hard disk from any accidental erasure. As examples of auxiliary memory device, there is an optical disk, a tape driver, and the like. However, such auxiliary memory device is expensive.
Generally, a video tape recorder is designed in a fashion that a video and an audio signals are recorded or read onto or from a video tape, i.e., a magnetic recording medium. It is a common practice that the video tape recorder is not provided with an additional function of storing data.
However, a medium or a large sized computer, or a workstation level computer, uses a tape driver which adapts a magnetic recording method and is added as an external data backup device. A lot of studies on the apparatus for backup of digital data using a video tape that adapts similar recording method have been performed.
A conventional data backup device using a video tape will be explained with reference to FIG. 1.
FIG. 1 shows a structure of the PC tape backup system of the Danmere Limited Co. of England.
Danmere Limited Co. produces a data backup system which uses a video tape recorder called "Backer 32", as a PC tape backup system.
To set a data backup system using the Backer 32, a PC interface card 10, i.e., an 8-bit industry standard architecture (ISA) type PC expansion card of model number "DANB100D", has to be installed in an expansion slot of a PC (or a host computer) 100. In addition, an external install type backup module 11, i.e, model number "DANF100B", is needed. An input/output connector of a video tape recorder (VTR, or a camera recorder) 200 is used for connecting the backup module 11 to the VTR 200. In addition, the Backer software of the Danmere has to be installed in the PC 100 so as to operate the PC interface card 10 and the backup module 11.
The PC interface card 10 and the backup module 11 receive backup data from the PC 100, add horizontal and vertical synchronous signals to them, convert them into a composite video signal, and input them to the VTR 200 via the input connector of the VTR 200.
Then, the VTR 200 records the backup composite video signal which is input from the backup module 11 onto a video tape using a method same as those by which the original composite video signal is recorded. The VTR 200 subsequently reads the backup composite video signal from the video tape in accordance with a request from the backup module 11 by a method same as those by which the original composite video signal is read, and provides the read signal to the backup module 11. That is, a backup composite video signal which can be obtained by converting the backup data is recorded and reproduced by a method same as those by which the original video signal input from an external device.
A user may generate a template of a file to be copied to a video tape via a graphic user interface. The template can occupy of an overall hard disk, directory,. or a file, or include a multiple directory.
The storage capacity of the Backer varies according to operation modes. Modes 1 and 2 allow recording performance of 9 megabytes per minute and 4 megabytes per minute, respectively. This means that data of 2 gigabytes and 1 gigabyte can be recorded onto a single video tape which has 4-hour recording capacity.
The conventional video tape data backup system has some problems. First, a PC interface card which functions similarly to "DANB100D" of Danmere has to be additionally installed into the expansion slot of the PC. Moreover, unnecessary space is required for the connection between the backup module 11 and the VTR 200. Furthermore, an additional power adapter 12 is needed for operating the backup module 11.
To connect a conventional video tape data backup device to a new PC, a PC interface card is detached from a PC and mounted onto the new PC. Then, a cabling work where the install type backup module is connected to a VTR and the new PC, has to be performed.
In such a conventional video tape data backup device, a user has to operate an application program of the host computer 100 if he/she intends to select a predetermined data of the host computer 100 and to backup the data onto the VTR 200. In addition, the user has to manually operate, record and reproduce buttons of the VTR 200. The trick functions such as fast forward, rewind, pause, and stop are controlled directly using a control panel of the VTR 200.
These operations are very cumbersome and the working efficiency of the video tape data backup device is deteriorated.
The conventional video tape data backup device receives backup data from a computer, adds horizontal and vertical synchronous signals to them, modulates the signals into a composite video signal, and stores (records) the result onto a video tape. Here, a pseudo composite video signal obtained by modulating the backup data is recorded onto a video tape by a low frequency conversion recording method by which an actual video signal input from an external device is recorded. The low frequency conversion recording method is that a luminance signal (Y) and a chrominance signal (C) are isolated from the video signal, and the luminance signal is frequency modulated while the chrominance signal is low frequency converted. Then, the two signals are superposed and recorded.
At this time, the backup composite video signal obtained by modulating the backup data is those as modulated by using only a luminance signal. The backup composite video signal includes horizontal and vertical synchronous signals. However, a modulation signal for the luminance signal is included while those for the chrominance signal is not included in the backup composite video signal.
This means that the frequency band for recording the luminance signal can be extended up to those allocated for the chrominance signal when data backup is performed. That is, the luminance signal can be frequency modulated to the frequency band which is extended up to those for chrominance signal, and recorded.
Functions for presenting a signal are enhanced as the frequency bandwidth becomes wider when the frequency modulation (FM) is performed. If the luminance signal is frequency modulated to the extended frequency band and recorded, the backup data of further increased amount can be recorded onto the video tape having a similar recording capacity.
However, the conventional video tape data backup device frequency modulates the luminance signal to the frequency band same as those for recording a common video signal and records the same when the data backup is performed. Therefore, the recording space of the video tape is not efficiently utilized, which causes a great loss of the amount of data record.